2. Center position of the Tx will not recorded in system initialization. Please calibrate your Tx after firmware upgrade. Some users moved the Tx stick while powering up the system, which would sent a false Center position to MC and cause bad flight performance such as flip over when taking off. This new firmware will not record center position any more.
Possible problem you may encounter: Tx travel range not symmetrical, causing mechanical stick center unmatch Tx signal center. Tx Trim/Calibration would be required.

6. Suggestions on IMU Calibration
a. Advanced calibration and Basic calibration are added to solve drifting issue during hovering.
b. Highly suggested to perform Advanced calibration when system cold start, which takes less time and more effective.
c. Perform Advanced calibration on time (Monthly) and Basic calibration at intervals to clean the error.

7. New style when taking off
Taking off is different. Motors will stay in idle under 50% throttle when you arm. Raise the throttle stick over center then hold, the copter will take off by itself. Once you bring it back to center, throttle will respond normally.